Rear derailleur is rubbing cassette

alewater

Member
Location
Colchester
Hi,

Newbie here.

Got my bike out today after not riding it for 3 years.

Fixed the rear flat tire and now the rear derailleur rubs against the cassette all the time, I don't remember it previously making that noise.

Google says I need to adjust the B Screw, I can tell you there is no B screw. There are two screws to adjust the H and L positions. Plus another that does literally nothing in any position.

I can't see what I'm missing, any ideas?

Thanks
A
 

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Ajax Bay

Veteran
Location
East Devon
:welcome:
Shimano Tourney RD. Has it got a model number somewhere eg RD-TY30? How many sprockets (?7) and what range (eg 14-28). How many positions on the rear shifter? How many clicks? Any text on the 'cable pulley wheel'?
Good pictures - thank you. Now please let's have two (bike the right way up) from the side: one with chain on large ring/large sprocket and one: small ring / small sprocket. Full chain in picture.
 
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the snail

Veteran
Location
Chippenham
A bit hard to tell from the pics, but in the 2nd picture the derailleur cage looks bent, so maybe you need a new one, possibly the hanger is bent too?
 

Ajax Bay

Veteran
Location
East Devon
I agree with @the snail - the RD cage's outer plate, down by the tension jockey wheel, is bent out. There should be almost no gap between the tab on the inner cage plate and the outer plate. And hanger verticality is worth checking too.
Doesn't solve the issue though.
 

fossyant

Ride It Like You Stole It!
Location
South Manchester
The bent cage shouts a few worries, and also, the B screw is there on the rear of the mech - you need to screw it 'in'.
 

gbb

Legendary Member
Location
Peterborough
Its my opinion that unless you know something changed, you shouldnt generally ever need to adjust derailleur screws.
I assume 3 years ago it rode ok, now it doesnt. That screams something else is wrong and adjusting screws will only (in all likelihood) make two things wrong, even if it does kinda correct the original problem.
As i say at work, fix the original problem, try not to fudge it.
 

Ajax Bay

Veteran
Location
East Devon
Size of largest sprocket please. @gbb - noone's suggesting adjusting the limit screws. My best guess, at this stage, is that the 'B' screw needs screwing in to drop the guide jockey wheel down, if that's what's rubbing. And we can see the 'B' screw is 'well out'.
The OP said "the rear derailleur rubs against the cassette all the time."
 

gbb

Legendary Member
Location
Peterborough
Size of largest sprocket please. @gbb - noone's suggesting adjusting the limit screws. My best guess, at this stage, is that the 'B' screw needs screwing in to drop the guide jockey wheel down, if that's what's rubbing. And we can see the 'B' screw is 'well out'.
The OP said "the rear derailleur rubs against the cassette all the time."
Adjusting screws mentioned by 3 contributors, OP included. My point is folk should carefully consider what's wrong before making adjustments or you could make things worse. 40 years of cycling I only ever had to adjust a RD once, when I fitted a new one. All things being even, they don't generally move on their own IME. Just an observation. :smile:
 
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